Circuit breaker



April 1934- s. s. GRADY 1,956,194

CIRCUIT BREAKER Filed Dec. 6, 1930 2 Sheets-Sheet .1

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50 415 i a I 50 31 j?? 4 3d 32 J4 51 45 42 v on I- \51 INVENTOR 1s 57 J?Jifi'radfl 59 4.9 56 2 50 B m I ATTORNEY April 24, 1934. s. s. GRADY1,956,194

CIRCUIT BREAKER Filed Dec. 6, 1930 2 Sheets-Sheet 2 INVENTOR ATTORN EYPatented Apr. 24, 1934 UNITED STATES PATENT OFFICE CIRCUIT BREAKER YorkFusoid Electric 00., Inc.,

a corporation of New Application December 6, .1930, Serial No. 500,503

10 Claims.

-This invention relatesv to circuit breakers in general and moreespecially to the use of small circuit breakers in homes and the like.

Among the objects of the present invention, it

is aimed to provide an improved circuit breaker for interrupting thecurrent in a-wiring system, both in case of light overloads and in caseof heavy overloads. I

It is another object of the present invention to provide an improvedcircuit breaker for interrupting the current of an electricalwiringsystem both'in case of light overloads and in case of.heavyoverloads, which circuit breaker depends upon an electric motive forceexclusively for actuating the interrupted elements, thereby dispensingwith springs and the like heretofore so extensively used.

It is still another objectof the present invention to provide animproved circuit breaker which can be compactly housed in a small casingto occupy a minimum amount of space.

It is a further object of the present invention to provide an improvedcircuit breaker of the class described which can be compactly "housed ina small housing to occupy a minimum amount of space and in which thecontacts are so separated by an interrupter when the circuit is brokenthat an arc can under no circumstances pass from one contact to theother.

These and other features, capabilities and advantages of the inventionwill appear from the subjoined detail description of one specificembodiment thereof, illustrated ing drawings in which Figure l'is alongitudinal section of .acircuit breaker made accordingto the presentinvention;

Fig. 2 is a plan of the same with the cover removed;

Fig. 3 is a fragmental side elevation showing the relative positions ofthe several parts when the circuit is interrupted;

Fig. 4 is a diagrammatic view of the several 'contacts and wiringarrangement with the casing removed;

Fig. 5 is a plan of the circuit breaker with the cover in place;

Fig. 6 is a vertical section, of the casing with the cover and metallicparts removed;

Fig. 7 is a plan view of the casing with the cover and metallic partsremoved; and

Fig. 8 is a perspective of one of the connecting arts. #In theembodiment illustrated, there is provided a main casing composed 01 asuitable insulating material, such asbakelite or the like,

in the accompanywhich, see Figs. 5, 6 and 7, preferably consists of ahousing member 1 and a cover 2.

The housing member 1 preferably has a main trough portion 3 formed bythe base 4, main side walls 5 and 6, intermediate end wall 7 andextension 8. To the rear of the intermediate end wall member 7, there isformed a rear end portion 9 which has at its lower end an extension 10.Between the intermediate wall member 7 and extension 10, there is formedan opening 11. F

To either side of the opening 11, there are formed extensions 12 and 13extending from the side walls 5 and 6 respectively.

The upper surfaces of the intermediate wall '7, extensions 10, 12 and 13are flush with one another and disposed in a plane below the upper edgeof the end portion 9. The upper slu'faces of the end portion 9 and sidewalls 5 and 6 are flush with one another. The lower surfaces of the endportion 9, extensions 10, 12 and 13, and side walls 5 and 6 to the rearof the intermediate wall portion 7 are preferably flush with one anotheras shown in Fig. 6 and disposed at a level above the level of the lowersurface of the base wall 4. i

The extension 8 is disposed at the rear end of the front portion 14 andextends from one side wall 5 to the other side wall 6. The upper surfaceof the portion 14 preferably is disposed at a level above the level ofthe upper surface of the. extension 8 and below the level of the upperedges of the side walls 5 and 6.

The cover 2 preferably extends from the rear face of the rear endportion 9 to the rear face of the end portion 14, the sides of whichresting on the upper surfaces of the side walls 5 and 6 and the rearportion resting on the extension 9.

The rear portion of the cover 2 is provided with two openings 15 and 16to register with the openings 17 and 18 in the end portion 9. At aboutthe middle of the cover 2, there is provided an elongated opening 19through which the handle for resetting the circuit breaker extends. Tothe front of the opening 19, see Figs. 1 and 2, there is provided adownwardly projecting ledge or baflle 20. The front end of the cover 2is provided with a downwardly extending flange 21 which extends downalong the front ends of the portions of the side walls 5 and 6protruding above the front extension 8. "I'he lower face of the flange21 rests on the upper surface of the portion 14 and is provided with aboss 22 having an opening 23 therein to register with the opening 24 inthe end portion 14. i

To either side of the opening 24 in the end portion 14, there are alsoprovided two larger openings89 and 26 which will behereinafterdescribed.

To the front of the bafile 20, there is formed in the cover 2 adownwardly facing recess 27 hereinafter to be described.

The operative parts of the circuit breaker will now be described.

In the trough formed above the base 4, there is located an electromagnet28 having a core 29 provided with an upwardly extending stem 30a. Theelectromagnet 28 is provided with a heavy winding 30 and a fine winding31. The rear end of the heavy winding 30 in the present instance isconnected to one end of the thermostat 32 preferably to the binding post33 which connects one leg of the thermostat to the upper surface of theextension 8. The other leg of the thermostat is preferably connected tothe bus bar 34 by means of the screw 35 which extends through the busbar 34 and thermostat into the extension 8 through the upper endthereof. The bus bar 34 as shown in Figs. 1 and 2 extends from the screw35 across the upper surface of the end portion 14 and is there providedwith the binding post 36.

The other end of the heavy winding 30 is connected to one end of thehorizontally extending member 37 which is provided with a spring arm 38,the front end of which is connected to the upper end of the extension 8by the screw 39.

The rear end of the spring arm 38 is provided with a cross piece 40having lateral wing portions 41, the lower ends of which are connectedto one another by the contact bar 42 adapted to engage the intermediatecontact member 43, the front end of which is also connected to the upperend of the extension 8 by the screw 39 being insulated from the springarm 37 by the insulated bushing 44.

The cross piece 40 is preferably connected to the spring arm 38 by abolt 45 as illustrated in Fig. 1. The screw head of the bolt 45 extendsabove the upper surface of the cross piece 40 in alinement with therecess 27, the recess 27 being formed to provide clearance for thisscrew head when the spring arm 38 and cross piece 40 are deflectedupwardly by the thermostat 32.

The rear end of the contact 43 is preferably bent downwardly to form thelip 46 extending rearwardly with its lower surface substantially inalinement with the upper surface of the extension 10 to engage the uppersurfaces of the lip 47 formed on the contact plate 48. The contact plate48 has its lower extended portion 49 secured to the extension 10 by thescrews 50. This lower extension 49 is connected to the lip 47 by thedownwardly extending portion 51 preferably resting along the rear faceof the intermediate wall '7 as illustrated in Fig. 1.

The portion 49 of the contact plate 48 is preferably connected to thebus bar 52 provided in the wiring system to which the circuit breaker isto be connected. The bus bar 52 is connected to the extension 49 by thescrew 53 which is passed through the extension 49 into the bus bar 52through the registered openings 15 and 17 of the cover 2 and end portion9 respectively.

In the diagram illustrated in Fig. 4, the end of the heavy winding 30connected to the thermostat 32 is shown as connected by the conductor 54and the end of the heavy winding 30 connected to the spring arm 38 isshown as connected by the conductor 55.

One end of the fine winding 31 is electrically connected to the frontend of the intermediate contact 43. In Fig. 4 the conductor 56 is shownas the means for connecting such intermediate contact 43 with the finewinding 31. The other end of the fine winding 31 is shown in Fig. 4 asconnected to the bus bar 34 by the conductor 57.

The bus bars 34 and 52 are of course connected to the main leads of thecircuit, to wit 58 and 59 in the usual way for interrupting the circuit.In the present instance, there are provided two interposers, the maininterposer 60 and the auxiliary' interposer 61. The main interposer 60is adapted to be actuated to space the lips 46 and 47 of the contacts 43and 48 from one another and thereby disrupt or interrupt the current atthis point.

The auxiliary interposer 61 is adapted to be actuated to space thecontact bar 42 from the intermediate contact 43. The auxiliaryinterposer 61 is secured to the upper end of the stem 30a of the core29. The main interposer 60 is provided with a recess 62 to receive thepin 30a which is adapted -to co-operate with the shoulder 63 at theinner end of the recess 62 to move the main interposer 60 rearwardlywhen the core 29 is attracted by the magnet 28.

In the operation of the device, the interposers 60 and 61 are disposedin the position indicated in Fig. l with the core protruding from themagnet 28 when the circuit is closed. The current passes from the lead58 through the bus bar 34, thermostat 32, conductor 54, heavy winding30, conductor 55, spring arm 37 and cross piece 40 to the intermediatecontact 43, fixed contact .48 and outgoing lead 59. Under suchconditions, a current of normal strength will pass through the circuit,including the thermostat and magnet without affecting eithersufliciently to move the core 29 rearwardly, and the circuit will remainclosed. Thereupon, in case of a light overload, the thermostat will beenergized by a slight excess of current and gradually deflect upwardlyuntil it engages the arm 38 and separates the cross piece 40 from theintermediate contact 43. Thereupon, all of the current will be directedthrough the fine winding 31, that is from the bus bar 34 through theconductor 5'7, fine winding 31, conductor 56, intermediate contact 43,fixed contact 48 and lead 59, in turn to attract the core 29, in turn tocause the interposer 61 immediately to pass between the cross piece 40,and intermediate contact 43 and further to cause the interposer 60 toforce the lips 46 and 4'1 from one another to interrupt the maincircuit.

In the case of a heavy overload or a short circuit, where the currentpassing from the bus bar 34 through the magnet 28 by means of thewindings 30 and 31 is sufiiciently high to excite the magnet 28 toattract the core 29, the interposer 60 will immediately be actuated tospace the lips 46 and 47 from one another to interrupt the main circuitat this point, that is the interposer 60 7 would then assume theposition indicated in Fig. 3. At the same time, the auxiliary interposer61 in the present instance, will also be actuated to separate the crosspiece 40 from the intermediate contact 43, that is the interposer 61would is actuated into circuit breaking position. To the front of theend portion 64 on the upper surface thereof, the interposer 60 isrecessed as indicated at 65. Intermediate the length of the interposer60, there is provided an opening 66 to receive the projection 67 of theconnecting plate 68. The connecting plate 68 is pivotally connected tothe stem 30a and is provided with an upwardly extending projection 69adjacent to the stem 30a and to the rear thereof to form an abutment forthe end of the coil spring 70 secured to the stem 30a and exercising atension on the projection 69 to urge the plate 68 in the direction ofthe side wall 5.

The connecting plate 68 is provided with a cam pin or projection 71extending upwardly there-- from at its rear end to engage the cam 72extending downwardly from and formed on the intermediate contact member43.

The cam 72, see particularly Fig. 2, inclines toward the wall 6 in itsforward direction. As a result, due to the co-operation of the pin 71with this cam 72 when the parts are disposed as shown in Figs. 1 and 2,the cam 72 acts on the pin 71 to hold the connecting plate 68 toward thewall 6,

against the urge of the spring 70, and when the connecting plate 68 ismoving rearwardly, the pins 71 is moved away from cam 72 and theconnecting plate 68 swings about the stem 30a in the direction of theside wall 5. On the other hand when the connecting plate 68 movesforwardly, it swings about the pin 30a in the direction of the side wall6.

The connecting plate 68 is provided with an elongated, longitudinallyextending" recess 73 to receive the lower end of the stem 74 of theresetting key 75. At the rear end of the opening73, a notch 76 is formedas a continuation of the slot 73 in the direction of the side wall 6.The shoulder 77 formed by the notch 76 serves as a perch for the stem 74so that when the key is rocked about the pin 78 when the plate 68 is ina rearward position, the plate 68 will be moved forwardly by theengagement of such pin 74 with such shoulder 77.

Due to the co-operation of the pin 71 with the cam 72 when the plate 68is so moving forwardly, the plate will be swung over toward the sidewall 6 to move the shoulder 77 out of engagement with the pin 74. Whenthe shoulder 77 has cleared the pin 74, then upon exciting the magnet28, the plate 68 may move rearwardly with the interposers 60 and 61without affecting the position of the key 75.

Thereupon to reset the plate 68, and interposers 60 and 61, it will benecessary to swing the key about its pin 78 so that the stem 74 movesrearwardly into the position indicated in Fig. 3 where the plate 68 willbe free to swing toward the side wall 5 when the pin '74 will againenter the recess 76 to co-operate with the shoulder 77.

Preferably as indicated, a coil spring 79 is formed around the pin 78connecting the key 75 with the interposer 60 to urge the handle portion80 of the key forwardly, the position indicated in Fig. 3, when theinterposer is actuated to circuit breaking position. Thus the pin '74will be swung back through the slot 73 of the connectmg member 68 andwill again enter the recess76 to cooperate with the shoulder 77.

The interposer 61 is adapted to slide on the upper face of theintermediate contact 43, the pin 30a to whichthe interposer 61 isconnected extending through the opening 81 formed in the intermediatecontact 43 and forming a path of movement for the pin 30a relative tothe intermediate contact 43 backwardly with the core 29 and againforwardly during the resetting operation.

The rear end 82 of the interposer 61 is also beveled to facilitatemoving the cross piece 40 upwardly when moved rearwardly. The uppersurface of the interposer 61 forwardly of the rear end 82 is recessedat;83, as indicated in Fig. 1.

When the interposer 60 moves rearwardly during a circuit interruptingoperation, the lower surface thereof will slide across the upper surfaceof the lip 47 and the upper surfaces of the extensions 12 and 13 over toand across the upper surface of the extension 10. When the interposer 60is located in final circuit interrupting position, it would thus beapparent that the extensions 10, 12 and 13 absolutely prevent an arc tojump around the edge of the interposer 60 from the lip 46 to the lip 47.

In order to lock the cover 2 to the casing 1, the screw 84 is providedextending through the opening 24 in the front end 14 of the casingl andengaging the threaded opening 23 in the projection 22 at the front endof the cover 2. The rear end of the cover 2 is secured to the casing 1by the screw 85 extending up through the opening 18 in the casing 1 andengaging the threaded opening 16 in the cover 2.

The downwardly extending ledge or baiiie 20 serves primarily to sparkthrough the opening 19 when an arc is formed between the cross piece 40and intermediate contact member 43.

3 The handle portion 80 of the key 75 is concentric at 86 and 87 withthe pin 78 and alines substantially with the ends of the opening 19 sothat the lower portion of the key 75 will substantially close theopening 19 throughout its pivotal movement and in any position of thekey 75.

From the foregoing, it will thus appear that the present inventionprovides a having a compact insulated casingfor the active parts. fullyenclosing the area in which any are may be formed so that the sparksfrom such are can under no circumstances escape out of the casing andthe circuit breaker will thus be clearly within the usual requirementsof underwriters for municipalities and the like.

It is also apparent from the foregoing that springs are entirelydispensed with for actuating the circuit breaker thus increasing thereliability of the device. I

From the foregoing, it will be seen that the present circuit breaker maybe supplied as a unit with the insulated housing ready to be installed.When so installed screw 88 is passed through the opening 89 in the endportion 14 of the casing 1 and then passed into the wall of the buildingin which the unit is to be attached. The other end of the casing isadapted to be attached to the bus bar 52 of the electrical equipment towhich the unit is to be attached, in which case as already explained,the screw 53 is passed through i the contact 48 into the bus bar 52. Thecircuit breaker is then completely and compactly cn closed in aninsulated housing which prevents the escape of any sparks from thecontacts both when the circuit is interrupted and when the key 75 Incase of a light overload, the thermostat 32 i will first be deflected toengage the spring arm 38 in turn to separate the cross piece 40 from theintermediate contact 43. Thereupon, the current will be forced to passthrough the fine windcircuit breaker v ing 31 and energize the magnet 28sufiiciently to attract the core 29 in turn to cause the interthecurrent passing through the windings 30 and 31 will sufiicientlyenergize the magnet 28 to attract the core 29 without first waitinguntil the thermostat 32 has become heated and deflected. Here again theinterposers 61 and will be moved rearwardly to separate the contacts asaforesaid.

. For resetting the interposers and again closing 1 the circuit, it isthen only necessary to actuate the handle portion of the key '75rearwardly. The stem '74 of the key '75 will then engage the shoulder'77 to move the connecting plate 68 forwardly, whereupon the interposer61 being fixed to travel with such plate 68 by the stem 30a, will ofcourse go forwardly and the projection 6'7 disposed in the path ofmovement of the shoulder at the forward end'of the opening 66 in theinterposer 60, will engage such shoulder 90 and move the interposer 60forwardly with it.

If the emergency has not passed, that is the cause for the overload orshort circuit still exists, the key '75wi1l not prevent the interposersbeing thrust rearwardly again by the magnet 28 since the stem '74 willhavedisengaged the shoulder '77 and the connecting plate 68, theprojection '71 as aforesaid co-operating with the cam plate '72 to causethe connecting plate 68 to move over toward the side wall 6, during theforward movement of the connecting plate 68. The spring '79 as indicatedwill yieldably serve to urge the key '75 to move with the interposer 60.On the other hand, due to this yieldable connection, after the key '75ismoved into circuit closing position, the position indicated in Fig. l,and the emergency, to wit the overload or short circuit has not yetpassed, the interposer will be free again to be actuated into circuitbreaking position although the key '75 may be held in circuit closingposition by an operator.

In the present instance, the bus bar 34 will constitute one of theterminals of the circuit and the bus bar 52 the other terminal of thecircuit to be connected by the circuit breaker.

To prevent tilting of the contact plate 68 when moving forwardly by thekey '75, there is provid-' ed the projection 91 extending downwardly andresting against the front face of the stem 800.

To insure the clearance of the shoulder '77 from the stem '74 at the endof the return movement of the plate 68 by the key '75, there is providedthe upwardly extending projection 92 on the side of the contact plate 68adjacent to the side wall 6.

This projection 92 has a cam vface 93 to cooperate with the edge of theintermediate contact 43 so that the elasticity of the contact 43 whenengaging this cam face 98 will act upon the same to move the connectingplate 68 the short distance required to permit the shoulder '77 to clearthe stem '74 at the end of the return movement of the key '75.

It is to be noted that the contact member 42, with'its supporting springmember 38, by which it is urged yieldingly against the intermediatecontact member 43, acts as a trip for the auxiliary interposer 61,standing in the path of sliding movement of the latter, and'so anchoringthe same in circuit making position until the thermostat 32, which issensitive to an overload, acts to raise the members 38 and 42 ashereinbefore described, thereby actuating said trip to release theinterposer, and at the same time break the contact between members 42and 48, to shut oil the passage of current through coil 30 ofelectromagnet 28 and deflect the entire current through the fine winding31, so that the core 29 is urged to actuate the interposers 60 and 61into circuit breaking position.

It is obvious that various changes and modifications may be made to thedetails of construction without departing from the 'general spirit ofthe invention as set forth in the appended claims.

I claim:

1. A circuit breaker device adapted to be included between suitableterminals in an electrical circuit, said device comprising, incombination, an enclosed insulated casing, a circuit breaker enclosed insaid casing, said circuit breaker having a fixed contact,anelectromagnet having a core, a yieldable contact normally inengagement 100 with said fixed contact, conductors for connecting saidelectromagnet and said yieldable contact in series, and an interposeroperatively connected to said core to separate said intermediate.contact from said fixed contact when said electromagnet is actuated inturn to actuate said core, said casing having a shoulder to receive saidinterposer in circuit breaking position and thereby cut off a freepassage around said interposer from the intermediate contact to thefixed contact.

2. A circuit breaker device adapted to be included between suitableterminals in an electrical circuit, said device comprising, incombination, a circuit breaker having a fixed contact, a yieldablecontact normally in engagement with said fixed contact, an electromagnethaving a core, conductors connecting said electromagnet and saidyieldable contact in series, an interposer operatively connected to saidcore for separating said yieldable contact from said fixed contact whensaid electromagnet is excited, a connecting plate operatively connectedto said core, there being a slot in said interposer, said connectingplate having a projection protruding into said slot, and a keyoperatively connected to said connecting plate to actuate the same inturn to return said interposer into circuit closing position.

3. A circuit breaker device adapted to be included between suitableterminals in an electrical circuit, said device comprising, incombination, an enclosed insulated casing, a circuit breaker disposed insaid casing and comprising a fixed contact, a yieldable contact normallyin engagement with said fixed contact, an electromagnet having a core,conductors connecting said electromagnet and said yieldable contact inseries, an interposer slidable relative to but actuatable by said coreto separate said contacts from one another when said electromagnet isexcited, a connecting plate connected to said core and operativelyconnected to said interposer, and a key pivotally connected to saidcasing and operatively connected to said connecting plate to actuate thesame in turn to return said interposer into circuit closing position. i

4. A circuit breaker device adapted to be included between suitableterminals in an electrical circuit, said device comprising, incombination, an enclosed insulated casing, a circuit breaker disposed insaid casing and comprising a fixed ieo contact, a yieldable contactnormally in engagement with said fixed contact, an electromagnet havinga core, conductors connecting said electromagnet and said yieldablecontact in series, an interposer slidable relative to but actuatable bysaid core to separate said contacts from one another when saidelectromagnet is excited, a connecting plate connected to said core andoperatively connected to said interposer, a key operatively connected tosaid connecting plate to actuate the same in turn to return saidinterposer into circuit closing position, and a spring for actuatingsaid connecting plate out of engagement with said key in circuit closingposition when said interposer and connecting plate are free to beactuated into circuit breaking position without affecting the positionof said key.

5. A circuit breaker device adapted to be included between suitableterminals in an electrical circuit, said device comprising, incombination, an enclosed insulated casing, a circuit breaker disposed insaid casing and comprising a fixed contact, a yieldable contact normallyin engagement with said fixed contact, an electromagnet having a core,conductors connecting said electromagnet and said yieldable contact inseries, an interposer slidable relative to but actuatable by said coreto separate said contacts from one another when said electromagnet isexcited, a connecting plate connected to said core and operativelyconnected to said interposer, a key operatively connected to saidconnecting plate to actuate the same in turn to return said interposerinto circuit closing position, and a spring for normally maintainingsaid key in circuit .closing position.

6. A circuit breaker device adapted to be included between suitableterminals in an electrical ircuit, said device comprising, incombination,

an enclosed insulated casing, a circuit breaker disposed in said casingand comprising a fixed contact, a yieldable contact normally inengagement with said fixed contact, an electromagnet having a core,conductors connecting said electromagnet and said yieldable contact inseries, an interposer slidable relative to but actuatable by said coreto separate said contacts from one another when said electromagnet isexcited, a con necting plate connected to said core and operativelyconnected to said interposer, a key operatively connected to saidconnecting plate to actuate the same in turn to return said interposerinto circuit closing position, a spring for actuatingsaid connectingplate out of engagement with said key in circuit closing position whensaid interposer and connecting plate are free to be actuated intocircuit breaking position without affecting the position of said key,and a second spring for normally maintaining said key in circuit closingposition.

'7. A circuit breaker device adapted to be included between suitableterminals in an electrical circuit, said device comprising, incombination, an enclosed insulated casing, a circuit breaker disposed insaid casing and comprising a fixed contact, a yieldable contact normallyin engagement with said fixed contact, an electromagnet having a core,.conductors connecting said electromagnet and said yieldable contact inseries, an interposer slidable relative to but actuatable by said coreto separate said contacts from one another when said electromagnet isexcited, a connecting plate connected to said core and operativelyconnected to said interposer, and a. key pivotally connected to saidcasing and operatively connected to said connecting plate to actuate thesame in turn to return said interposer into circuit closing position,the casing having a slot to permit the key to protrude therefrom.

8. A circuit breaker device adapted to be included between suitableterminals in an electrical circuit, said device comprising, incombination, an enclosed insulated casing, a circuit breaker disposed insaid casing and comprising a fixed contact, a yieldable contact normallyin engagement with said fixed contact, an electromagnet having a core,conductors connecting said electromagnet and said yieldable contact inseries, an interposer slidable relative to but actuatable by said coreto separate said contacts from one another when said electromagnet isexcited, a connecting plate connected to said core and operativelyconnected to said interposer,

and a key operatively connected to said connecting plate to actuate thesame in turn to return said interposer into circuit closing position,the casing having a slot to permit the key to protrude therefrom, saidkey having outwardly extending arcuate surfaces to co-operate with theends of said slot when pivoted thereby constantly to maintain the slotclosed during movement thereof.

9. A circuit breaker device adapted to be included between suitableterminals in an electrical circuit, said device comprising, incombination, an enclosed insulated casing, a circuit breaker disposed insaid casing and comprising a fixed contact, a yieldable contact normallyin engagement with said fixed contact, an electromagnet having a core,conductors connecting said electromagnet and said yieldable contact inseries, an interposer slidable relative to but actuatable by said coreto separate said contacts from one another when said electromagnet isexcited, a connecting plate connected to said core and operativelyconnected to said interposer, and a key pivotally connected to saidcasing and operatively connected to said connecting plate to actuate thesame in turn to return said interposer into circuit closing position,the casing having a,

slot to permit the key to protrude therefrom, said casing having abaflle extending inwardly adjacent to said slot toprevent the escape ofany sparks.

10. A circuit breaker device adapted to be included between suitableterminals in an electrical circuit, said device comprising, incombination, an enclosed insulated casing, a circuit breaker disposed insaid casing and comprising a fixed contact, a yieldable contact normallyin engagement with said fixed contact, an electromagnet having a core,conductors connecting said electromagnet and said yieldable contact inseries, an interposer slidable relative to but actuatable by said coreto separate said contacts from one another when said electromagnet isexcited, a connecting plate connected to said core and operativelyconnected to said interposer, a key operatively connected to saidconnecting plate to actuate the same in turn to return said interposerinto circuit closing position, means for actuating said connecting plateout of engagement with said key when actuated into circuit closingposition, said means including a cam co-operating with said yieldablecontact to snap said connecting plate out of engagement with said key,and a spring for moving said connecting plate into position for theco-operation of said cam with said yieldable contact.

STEPHEN S. GRADY.

